package summer_vacation.cullen.four10;

/**
 * Created by Cullen on 2015/8/13.
 */
public class N45 {
    public static void main(String[] args) {
        int sum=1;
        int s=1;
        for(int i=2;i<=20;i++)
        {for(int j=i;j>1;j--)
        {
            s=s*j*(--j);
        }
            sum=sum+s;
            s=1;
        }
        System.out.print("1!+2!+3!+....+20!="+sum);

    }
}
